The invention relates to a pipe arrangement for incorporation into a delivery pipeline extending from a borehole delivering liquid from a well by means of an immersion pump.
Delivery boreholes in wells containing mineral deposits generally have a protective casing comprising a filter or perforated pipe in the lower part and a riser pipe in the upper part. A delivery pipe inside the casing has an immersion pump connected to the lower end thereof and installed in the borehole for delivery of the liquid to the surface. In such boreholes the monitoring of the behavior of the deposit surrounding the bore and hydraulic pressures in the strata during the entire delivery time is of great importance, since this, together with other delivery and deposit data afford a control of the output of a deposit.
Previously, in the case of such boreholes, a direct measurement of the hydraulic pressure in the well, as well as of the pressure build-up on stoppage of the delivery, has not been possible because pressure-measuring devices cannot be lowered in the annular space between casing pipe and delivery pipe. Lowering a measuring device in the delivery pipe is of no use, because the measured pressures are affected by the potential energy of the fluid column standing in the delivery pipe when, as is usual, a check valve is provided which prevents the dropping of the fluid column upon operation stoppage. Even if the check valve were omitted, this measurement would give information on pressure data in the area of the inlet opening of the immersion pump only after shutting down the immersion pump. Electrical measuring methods, which are useful at shallow depths within rough limits of accuracy, are not technically feasible for great depths and high pressures.